Automatic telephone system



Patented June 14, 1927,

`UNITED STATES `ement orrice. *y

FRITZ LBBERGER, OF BERLIN-SCIEIMARGENDURE AND EDGAR HAHN, OF CHARLOTTENBURG, GERMANY, ASSGNORS TO SIEMENS t HALSEE AKTLENGESELLSCEIAFT,WERNERWERK, OF SIEMENSSTADT, NEAR BERLIN, GERMANY.

AUTMATIC TELEPHONE Application filed July 2, 1925, Serial No. 40,980,and in Germany V.'luly 18, 1924.

ln the co-pending l application of Lubberger Serial No. 41,034 filedJuly 2, 192V, of even date and its Figs. 1 to 3 is described andillustrated a method of setting up incoming and outgoing calls in atelephone system comprising main and sub-exchanges arranged forautomatic operation. The invention described in the said disclosureenablessingle and multiple metering to be etlected tor such calls vandenableel a sub-exchange subscriber to be connected to the toll er:-change. The invention also enables the local battery at the sub-exchangeto be re placed by a source ot current at the main f exchange, whichprovides the battery Voltage for operating and holding the switching devices at the sub-exchange, this batteryl voltage being taken over one ofthe two speaking leads to the switching members at the subexchange. Itthe line resist-ance be high owing to the great distance between thesubeizchange and the main exchange, and il turtliermore relays,resiet-ances, and choking coils be inserted in the lead, over which theholding battery current is taken from the main to the` sub-exchanges (inthe above mentioned application this is taken over the speaking leadl5), then the drop ot potential in the line may be so great that theVoltage is insutlicient to operate and to hold the switching members atthe sub-exchange The present invention removes this detect by using onespecial battery lead, Which, in ad: dition to the c and b speaking leadsot' the individual trunk lines, connects the sub-ei;` change With themain exchange,`and at the sub-exchange this special lead is connected bya relay to the individual batteryy leads ot' the switching members to beoperated or held. l

lllith reference to the above mentioned application, a detaileddescription will be given hereafter ot the switching operations forsetting up an outgoingcall from the subscriber N 300 ot the sub-exchangewhen a relay BA is used for connecting up the battery, which' relayfunctions when its circuit is closed.

rlhe drawing shows in Figs. 1 and 2 by Way of example one circuitarrangement.

l/Vhen the subscriber N 300 originates a call,

the following circuit is closed:

ilJ Earth, cattery, baclt. contacts cf 401 and contact (t 301. in eachtrunk line; thereby an earth potential is applied to the batteryconnecting up relay of each trunk line. The relay BA 100 in the trunkline VL I isoperated in the following circuit: l

2. Earth,battery,back contacts of 401 and o 401, relay R 400, leads bal103, choking coil Dr 100, relay BA 100, double front conl tact a 301,earth.

Thereby in each trunk line a contact be' 101 o1 the `battery connectingup relay BA 100 connects the battery supply lead of the relays, one ofwhich is associated with each trunk line (lead batt 101 in VL I), to thebattery supply lead batt 100, which is common to alltrunk lines comingfrom the main exchange. rIhe coupling relay K 100 ot the virst idletrunk line and the relay C 100 are operated over:

3. Earth, double front contact t 301, relay K 100 Winding I, lead @al101, relay C 100 Winding I, back contacts Z 103, zo 103 and asp 201,battery supply lead batt 100. The relay K 100 closes the operatingcircuit for the relay t 300 and closes the holding circuit tor therelays K 100 and C 100 as tolloWs:

4. Earth, relay T 300, Winding II of relay K 100, front contact 7: 103,lead dd 101, Winding H of relay C 100, battery lead batt 101, frontcontact ba 101, battery supply lead batt 100. Y

The battery connecting up relay BA 100 of the trunk line VL I is lockedover the contact c 103 of the relay C 100, While the relay T 300 at itscontacts t 301 and t 303 connectsthe calling subscriber through to thetrunk line and marks him engaged to incoming calls by short circuitingthe relay A 300 at the front contact t 305. Thus the relay BA 100 of thetrunk line taken into use is further maintained energized by theoperation ot the relay C 100 after the calling subscriber been switchedthrough.x the the battery connecting vup relaysl-ll'i of the other`trunk lines are rendered operable by the subscribers calling relay A300, which has been de-energized after the back contact t 305i has beenopened and ithas been short circuited at the l'ront contact v305. rlherelays fall back and again disconnect the batterysup Vply leads of theindividual trunl; lines from thebattery supply lead batt 100.V

The calling, subscriber has new been' connected through Vas lar asthepreselector associated with his `tr'tinli line at they main exchange: Y

5. .Eartlnbatter front Contact ,r 4.01,

"relay R 500, back contact 501, lead ad 103, back Contact Z 103, lead ad101,1'ront contacts L 101 and t 301, subscriber"s station Nl300`, numberdial contact 'nu 300, front contacts t 303 and 71: 10:2, lead (M101,

L Arelay B100, earth.

' The relay R' 500 at the main exchange and the relay B 100 at thesub-exchange :are

operated.AV rEhe Vrelay R 00 thus starts)y up the preselector, Which inlrnotyn manner (see aboye'V mentioned application) hunts Y Yfor an idlelirst group selector and connects through'the leads ad 103 and bd 103 tothe lirst, group selector, the relays M 400 and V 400 being operated atthe saine time. The operation olf thev relay B 100 causes the backcontact I) 103to be once opened and y at the front Contact 5101 therelay D 100 `is energized as follows:

y ll. Earth, front Contact Z) 101, relay -D 100, battery VleadV batt101, Yliront contact ba "101,` battery supply lead batt 100.

Thereupon until the release of the connection, the ,relay D 100 loelsitself over: 7. Earth', front Contact Z 101, relay D 100, battery leadVbatt 101, front Contact a 101, battery supply lead bott 100.

The front Contact (Z104 renders the Y second trunk line available for anincom- 'tion at the main exchange, the selectin O opi'ng or outgoingcall byconnectingthe battery supply lead batt 100 toV theY trunk line VLHover the back contacts asp 201 and zo 103, 'trent contact (Z 104', backContact d Il. Thefront Contact (l 10Q prepares the metering circuit.

The further building upY of 'the conneceration and they switchingthrough ol' the' @peaking leads to the lrantedsubscriber are f describedin the above mentioned applica and D 103, front ContactV 7c 10;l, meterZ,

300, front Contact 7c 105, battery lead batt 101, front contact ea 101,battery supply Y lead batt 100.,

l'ile'teringr having end-ed, the lirst group Vselector releases; relay M100 falls bach and at contact mi L103 it interrupts the circuit ol relayV400, Which falls baeli alter some time as it is very slow acting.

Thus during` the time taken by the relay V 100 to release, the batteryis disconnected from the lead ed 103. The relays R 4.00 and BA fallback; the relay BA 100 at its `Contact Zia 101 opens the battery leadbatt 101 for the relays ol' trunk line VVL l. r1`he relays 'C 100Winding ll, K 100 Windingjr ll, D 100 and T 300 fall back.

Foi-,calls from the main exchange to a subscriber N 300 of thesulrexchange the callingrelay AR 100 oit the trunk line is energizedalter the preseleetor belonging to a trunk line'goin'g rto thesub-exchange has been taken into use 'from the second Kcircuiti selectorover the leads mi 103 and er! 101 (see aforementioned application). VtContact (w1 1041 the relay All 100 cennects up the battery conneeting uprelay BA 100.

9. Earth, battery, baci; Contact 101, Mliront Contact m L101, relay ll-100, leads ed 103 and ed 101, choking coil Dr 100, relay BA 100, front'Contact er 104;, earthn The relay Bri 100 is operated and at its contactZut 101 it connects the battery lead batt 101`With the batterysniff-pl;Y lead tft/,tf 100. Furthermore the relay ZV 100 operated asfollowsf f 10Q Earth, front Contact ai' 101, relay ZV 100, battery leadLait 101. iront Contact 72a 101, battery supply lead batt 100. At itsdouble Ytrent 'Contact ,er 102 the relay closes a holding' circuit 'foritself and a holding' circuit for the relay BA 100. The contact zu 101opens the lead ed 101, hence the iu'eter Z 300 cannot operate. Theconlact .er 104i renders the trunk line VL 1l available over:

11'. Battery supply lead bait 100v` bark contact asp 201, front Contact.zo 104.-, back ils Vcontact CZ Il, lead afl 102 ot the trunk line VL1I. The selection of the subscriber N 300 of the sub-exchange .takesplace in the llll ing` relay A 300 associated with his line is energizedover the exciting,` circuit:

12. Battery supply lead batt 100, 'liront contact Zio 101, battery leadbatt 101, 'front contactr fm Q02, relay ll" 200, t'ront contact z' 32,relay A 300, earth. The latter closes its double lront contacts c 301,etc., in all the trunk lines VL, and thus causes the relays C 100 and L100 to operate in the trunk line VL Yl over the 'following circuit:

125. VEarth, double front contact e 301, relay l'f. 100 windlngl, leadcfZ 101, relay C 100 winding l, trent Contact m 201, relay L 100,battery lead hatt 101, front contact Za 101, battery supply lead batt100. The re lays l( and C in the other trunk lines VL cannot operate,because the relays AS) 200 and lll Q00 have been operated at the end otthe selection, as shown in the alforenienu tioned application. rllherelay L 100 locks over:

1.a. Battery supply lead bott 100, trent contactta 101, battery leadZfZZ'Z' 101, relay L 100, trent contact Z 102, resistance lWL 100, backcontact b 1022, earth, and connects at its :trent contact Z 1011 thelead ofZ 101 to the source ot ringing current. AThe relay K 100 closesthe following circuit, in which it as well as the relay C 100 is lockedand the relay T 300 is energized.

15. Earth, relay T 300, relay l 100 winding I1, front contact c 103,lead cZcZ 101, relay C 100 Winding Il, battery lead batt 101, frontcontact Zia 101, battery supply lead batt 100.

The relay C 100 at its contact c 101 disconnects the earth potentialfrom the calling` relay ot the trunk line VL l. The re lay AR 100 allsback. The relay T 300 at .its trent contacts t 301 and t 303 connectsthe wanted subscriber N 800 to the, speaking leads UZ 101 and ZJCZ 101,hence the snbscrib er is now called over the following circuit:

1,6. Earth, battery, source of ringing` cnrrent, 'liront Contact Z 104,lead MZ 101, trent contacts Z: 101 and 301,subscribe1"s station N 300,number dial contact mi, 300, front contarts t 303 and 7s 102, lcadrfZ101, relay B 100, earth. The relay P) 100 does not respond toalternatingl current. TVhcn the wanted subscriber answers, batterycurrent flows over Vthe last mentioned circuit and the relay B 100 isoperated. At its front contact Z) 102 it disconnects the holding,-circuit ot the ringing relay L 100 and at its front Contact Z 101 itconnects up the relay D 100. The relay l.; 100 releases and at itsContact Z 108 it Vcloses the a lead afZ 101, so that the speaking routeis now closed between the two subecribers.

At the end ot the conversation, when a subscriber hangs up his receiver,it will be seen from Fig. 8 of the aforementioned application that therelay M 400 at the preeelector VW is deenergized, the relay relt thewanted subscril'ier N 300 bo engaged when a call arrives from the mainexchange,

the relay F 200 is energized in the `l'ollmring` circuit at the end elthe numerical selection. 17. Battery supply lead Zia/t 100, itrontContact Zw 101., battery lead hatt 101, front contact m 202, relay E2.00, trent contacts 32 and I; 305, earth. The relay F L00 connects upthe busy tone relay BR 100 over:

18. Earth, bach conta ct Z 101., t'ront contact ljt' 201, relay BB 100winding ll, battery lead bett 101, Ytrent Contact ZM, 101, batterysupply lead Zunft 100. rthe busy tone relay lillJ 100 lccls'itsel'liover the o speaking lead (battery.

at the lead MZ 101 at the second group selector, preselcctor wiper V`W(Z), see the aterementioned application, and thence over:

19. back coirtactal 501,-'tront co-rtact Z' 502,y lead ad 103, backcontact Z 10?), lead al 10.1, back contact C 101, front contact Z211102, relay BR 100 windingl Il, earth.

At its Contact Zr 101, the relay BR 100 disconnects the calling, relayAR 100 :trom the lead afcZ 101. The relay AR 100 is deenerprized andopensv its contact m" 104. rlhe battery connecting' up relay BA 100 ismaintained energized over the contact zo 102 until the release. rllhecalling subscriber is given the busy tone over an induction coil windingon` the relay BR 100 and the lead MZ 101 and MZ 103. Upon the release,the relays M /100 and V 1-00 at the main exchange and the relay BA 100at the sub-exchange are deenergized. Upon releasing', the relay 11A, 100opens the battery lead hat?? 101, hence the relay ZV 100 talls back.

It the sub-exchange be provided with a battery connecting up relay (BA100) operated by cnrrent normally flowing.: over the line Jfrom the mainexchange, the circuit changes are similar to those above described :torincoming and ontaoinggj calls to and 'trom the snb-exchange (Fig. 2.)V

Normally the relay BA 100 is energized as fellows:

20. Earth, battery, back contacts (7 101 and c 4101, relay R 100. leadZNZ 103, choking` coil Dr 100, relay BA 100, earth.

Thus the battery load batt 101` ot the trnnlrline VL I is normallyconnected to the comlnon battery supply lead batt 100 by the Contact Za101. Hence the relay R 400 at the main exchange is not energized overthe high resistance winding of the relay BA 100, and it only operateswhen, upon a subscriber of the sub-exchange (ll 300) being called, thecalling relay A 300belongingy to this subscriber is connected in shunttothe relay BA 100.

By a call of the subscriber N 300 of the Vsub-exchange the relay lt L100at the main 201, battery supply lead batt 100. The fui:-V

ther circuit changes and switching through operations, as well. Vas theselecting, take4 place in the manner above mentioned. The release iseffected after the conversation has ended Vand the metering operationhas been completed; this entails as before the deenergization of therelays M 100, V 100 at the main exchange. During the time taken by therelay V400 to release slowly, the lead bd 103 loses its voltage, therelay BA 100 at the sub-exchange now. falls back and interrupts thebattery supply lead batt 101 of the holding relays at the sub-exchange,hence the relays can return to their normal position. y

Since the relay BA 100 is normally energized, battery voltage is appliedto the battery supply lead of the switching relay of each trunk line VL.when a call is made from the main exchange to the sub-exchange.

Only when release takes place, is battery` disconnected from the lead71d 103 by thie contacts m 101 and v 101 at the main ex-y change;thereby the relay 'BA 100 and the holding relay at the sub-exchangerelease as before, i,

`1What is claimed is:

1. lnan automatic telephone system, a

- main and a subexchauge, a group of trunks between said exchanges, asource of current at said main exchange, a single battery conductorbetween sai-d exchanges, automatic switching equipment: in saidexchanges, subscribers lines terminating in said exchanges,

means controlled by a calli ng subscriber for and means for opera-tingsaid relay from the main exchange battery over the associated trunk,said relay operating to connect the switching` equipment associated withthe selected trunk with saidbattery supply conductor.

3. In a telephone system, a main and a sub-exchange, a group of trunksbetween said exchanges, said group comprising talk ing` conductors and abattery supply conductor, switching` equipment in said: exchanges, asource of currentat said main exchange, a battery control relay in saidsubexchange, subscribers lines terminating in said exchanges, meansresponsive to the re-V moval. of the reeeiver'from one of said sub-'exchangesubscribersr lines for energizing vsaid exchanges, a relayassociated with each of the trunks of said group arranged to connectthat part of said switching equipment associated with that trunk to thebattery conductor, means responsive to the initiation of a call by oneof said subex change subscribers for energizing all of said relays,means for selecting one of said trunks, and meansrfor releasing all ofsaid relays exceptt-he one associated with said selected trunk. Y

5.111 an automatic telephone system, a main and a sub-exchange, aplurality of trunks between said exchanges, a source of current at saidmain exchange, a battery conductor common to said trunks between saidexchanges, switching equipment in said exchanges` a relay atsaidsub-exchange as` sociated with each of said trunks, contacts in saidbattery conduct-or controlled by said i In witness whereof, I hereuntosubscribe my name this 12th day of June, A. D. 1925.

EDGAR HAHN.

